Nothing so fills the heart with contrition and humbles the soul as solitude embraced with self-awareness, and utter silence. And nothing so destroys the state of inner stillness and takes away the divine power that comes from it as the following six universal passions: insolence, gluttony, talkativeness, distraction, pretentiousness and the mistress of the passions, self-conceit. Whoever commits himself to these passions plunges himself progressively into darkness until he becomes completely insensate.
But if he comes to himself again and with faith and ardor makes a fresh start, he will once more attain what he seeks, especially if he seeks it with humility. Yet if through his negligence even one of the passions that we have mentioned gets a hold on him once more, then the whole host of evils, including pernicious lack of faith, moves in and attacks him, devastating his soul till it becomes like another city of Babylon, full of diabolical turmoil and confusion (cf. Isaiah 13:21). Then the last state of the person to whom this happens is worse than his first (cf. Matthew 12:45), and he turns into a violent enemy and defamer of those pursuing the path of hesychasm, always whetting his tongue against them like a sharp double-edged sword.
~St Gregory of Sinai